Method for removal of broken spark plugs



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2 Sheets-Sheet l Filed NOV. 27, 1946 INVENTOR.

Patented Apr. 10, 1951 `UNITED .STATES PATENT OFFICE vraslw Marilou Fon,REMOVAL F BRKEN SPARK PLUGS Henry Leland Van lerinark, also know-'n asHenry L. Van Dermark, deceased,.late of Sacramento,

C alif., by Hazel L. Van Dernark, executrix,

Medford, Oreg.

Application November 27, 1946, Serial No. 712,612

2 Claims. (Cl. 29-4148) (Granted under the act of March 3, 1883, as

amended il'ril S0, 1928; 370 i). G. 757) The .invention described hereinmay be ymanufactured and used by or `for the Government for governmentalpurposes without payment ofA any royalty thereon.

This inventoin relates to a method of removing broken spark plugs frominternal combustion engines, particularly those of aircraft. The methodis applicable particularly to such engines, the cylinder heads of whichare provided with dual ignition from spark plugs located in opposedrelation in the head. The method is of Ygeneral application to sparkplug ignition engines however, provided that they have the necessaryopenings for the introduction of tools as will be described.

In the past, an obstinate broken spark plug necessitated removal of thecylinder head. Often, if the head was not removed, broken pieces ofmetal or porcelain (chips) dropped into the cylinder and created scoringor even worse trouble in the cylinder.

One object of the invention is to enable removal of a broken plugwithout taking off the `cylinder head.

Another object is to prevent dropping of metal or porcelain chips insidethe cylinder.

Another object is to provide a powerful bite for the removal tool intothe shell of the broken plug.

Referring now to the drawings:

Fig. 1 is a perspective view in vertical section of an aircraft cylinderhead showing a broken plug inits left plug recess.

Fig. 2 is a side elevation or air blast tube tion.

Fig. 3 is a phantom view of the aircraft cylinder head corresponding toFig. 1 showing the chip removal tool in full view.

Fig. 4 is a fragmentary view corresponding to Fig. 3 showing thedrilling tools ready to be applied.

Fig. 5 is a stop drill shown on a larger scale than in the precedingligure.

Fig. 6 is a plan or end View of the drill jig shown in perspective amongthe tools shown in Fig. 4.

Fig. 'l is a side elevation of the drill jig.

Fig. 8 is a view corresponding to Fig. 4 with the substitution ofremoval tools for the drilling tools. Fig. 9 is a side view of aVsplined removal tool.

Fig. 10` is an end view of the splined removal tool shown in Fig. 9.

In the figures, I5 is a vertical section of a cylinder head having twospark plug recesses or ports I6 and I 1, these being at' the left andright hand, respectively. Both are fitted with threaded bushof a chipremoval tool which forms a related invenings Ilia and Ila, respectively.Within the bushing I6a there is shown a broken spark plug I6.

n The iirst step in the method after knocking `out the 'porcelain coreis the insertion through the port Il of the chip removal tool or airblast tube I9 shown in Fig. 2 above and in Fig. 3 locked in place foruse. The tool itself comprises a tube 29 having on its outer end a softrubber gasket 2| and a shoulder 22 to support the gasket. At theopposite or inner end there is a ferrule or connection 23 for the chuck24 of an air hose 25 (see Fig. 3). A threaded sleeve 26 is adapted to bescrewed into the threaded bushing Ila to make a substantially air-tightjoint about the tube 20. When the sleeve 26 is tightened after thegasket 2| has been brought against the bottom of the broken plug I8, thetool will occupy the position shown in Fig. 3. As soon as this positionis attained, air pressure, say 20 pounds per square inch, is turned onthrough the hose 25. Chips will then be blown out as they becomeloosened.

The pressure is maintained as long as there is any likelihood of chipsbeing formed.

Referring now to Fig. 4, 30 is a drill bushing having a body 3| providedwith a hexagonal shouldered portion 32 and a threaded extension which isprovided with four flutes 34. Four equidistant holes 35 extendlongitudinally through the hexagonal portion 32 and the'body 3|. Theutes 34 are extensions of the holes 35. The threaded portion 33 ts thethreaded bushing I6. In use the jig 30 is screwed into the bushing I6until it abuts the shell of the broken plug I8. A stop drill 36 whichfits holes 35 with a running Iit is now inserted into each hole 35 inturn and the top of the shell I8 is drilled until a stop 31 preventsfurther entry. An electric drill 38 is used to drive the drill 36.

The result of the above operation is that the spark plug shell I8 is nowprovided with four internal utes 39 as indicated in Fig. 8. Since theshoulders of the flutes 39 are rough, the interior of shell I8 is handreamed by means of a reamer 49 and a hand wrench ill. After thisoperation, a splined tool 42 is inserted so that the splines i3 thereofextend into the flutes 39. Since the splines are sharp on the one edge43a as shown in Fig. 10, an excellent bite is provided in the directionof reversal of the spark plug threads, i. e., in a direction that willunscrew the plug. The splined tool 42 is thenrotated until the plug |6is clear of the port I6.

The invention claimed is:

l. The process of removing a spark plug from an engine cylinder whichcomprises removing the porcelain core of the spark plug, inserting andlocking an air blast tube in such a position on the remainder of theplug so that the air blast proceeding from said tube will blow away fromthe engine cylinder, placing the spark plug to be removed under airpressuer applied through said air blast tube, placing a drill bushingprovided with openings over said spark plug, drilling openings in apredetermined pattern in the periphery of the shell of the plug,discontinuing the air pressure after there is no chip formation,applying a tool which fits the openings simultaneously and thenunscrewing the plug by rotating the tool.

2. 'I'he process of removing a spark plug from an engine cylinder whichcomprises knocking out the porcelain core of the spark plug to removesame from the plug shell, inserting and locking in place an air blasttube against the bottom of the plug shell, placing the spark plug shellunder air pressure applied through said air blast tube to blow chips ina direction away from the cylinder, placing a drill bushing withopenings over said plug shell, drilling the openings in a predeter- 4mined pattern in the periphery of the shell, discontinuing the airpressure after chip formation ceases, applying a turning tool which fitsmore than one of the openings drilled into the spark plug shell and thenunscrewing the plug by rotation of the tool.

HAZEL L. VAN DERMARK, Execatrix of the Will of Henry Leland Van Dermark,also known as Henry L. Van Denmark, Deceased.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS

